1. Field of the Invention
This invention relates to a medicament carrier, and more particularly, to a carrier containing a dry powder medicament adapted to be housed within an inhalator usable by asthmatics and the like. By inhaling on a mouthpiece, a prescribed dosage of the medicament is entrained in an air stream and inhaled by the user through the mouthpiece to coat the lungs of the user.
2. Description of the Prior Art
Asthma and other respiratory diseases have long been treated by the inhalation of an appropriate medicament to coat the bronchial tubes in the lungs to ease breathing and increase air capacity. For many years the two most widely used and convenient choices of treatment have been the inhalation of a medicament from a drug solution or suspension in a metered dose aerosol, pressurized inhalator, or inhalation of a powdered drug generally admixed with an excipient, from a dry powder inhalator. With growing concern being voiced over the strong link between depletion of the earth's atmospheric ozone layer and chlorofluorocarbon emissions, use of these materials in pressurized inhalators is being questioned, while an interest in dry powder inhalation systems has accordingly been stimulated.
Small quantities of a fine particle, preferably micronized powder, are used mainly for therapeutic purposes in treating diseases of the respiratory tract. Powders of this type, such as salmeterol hydronapthoate, in quantities generally below 50 micrograms (.mu.g) are added to the respiratory air of the lung of the patient. It has been found that the particles of active materials should have a particle size of less than 5 microns (.mu.) in thickness to insure that they penetrate deep into the lung. Thus, the metered dose must be atomized, aerosolized, or sufficiently broken up for inhalation by the patient to achieve the desired effect in the required dosage.
In copending application Ser. Nos. 08/025,964, filed Mar. 3, 1993, to Mulhauser et al, entitled "Dry Powder Inhalator Medicament Carrier", and 08/143,182, filed on or about Oct. 26, 1993, entitled "Dry Powder Medicament Inhalator", by inventors Mulhauser et al, and assigned to the same assignee as the present invention, a woven or nonwoven screen mesh disc or medicament carrier is disclosed which has perforations impregnated at spaced locations along its circumference with a dose of powdered medicament, such as salmeterol hydronapthoate, which is useful in the treatment of asthma. The carrier is selectively indexed so as to present the impregnated doses of medicament seriatim between a pair of holes in an upper and lower pressure plate in an inhalator. Air is forced through the holes in the pressure plates and the perforations in the encapsulated carrier to entrain a dose of the powdered medicament, which is then inhaled through a mouthpiece, by the patient-user.
Because the powdered medicament is impregnated into the carrier and spans a number of perforations or interstices formed therein, the air impinging upon the carrier and the powdered medicament will cause the medicament to break up as it is pressed up against and passed through the infrastructure to aerosol or atomize the same so that the medicament is presented in appropriate particle sizes for maximum benefit when inhaled. Further, due to the porous nature of the carrier and the interstitial deposit of the medicament, turbulent air can completely surround each medicament dose and entrain it, to assure complete dispensing of the medicament dose from the carrier into the air stream. The turbulence can be created in the air flowing through the carrier by passing it through a nozzle and bottom pressure plate in such a manner to create pressure changes resulting in turbulence of the air as it passes through the carrier to assist in breaking up the compressed dose.
This invention relates to such medicament carrier structures which lend themselves to mass production.